14.4 Energy Conservation and Satellite Motion ­ 14.6 Escape Speed.notebook
January 27, 2017
Satellite Motion
The sum of the KE and PE of a satellite is constant at all points along its orbit
• circular orbit:distance from center the same so PE and KE the same
• velocity is constant
Elliptical orbit, speed and distance vary
• apogee: farthest point from Earth's center
> PE greatest, KE least
• perigee: closest point from Earth's center
> KE greatest, PE least
Kepler's Laws of Planetary Motion:
1. the path of each planet around the sun is an ellipse with the sun at one focus
2. each planet moves so that an imaginary line drawn from the sun to any planet sweeps out equal areas of space in equal time intervals
3. the square of the orbital period of a planet is directly proportional to the cube of the average distance of the planet from the sun
Escape speed: minimum speed necessary for an object to escape permanently from a gravitational field
At Earth's surface any more than 62 MJ/kg, or a speed of 11.2 km/s (neglecting air resistance)
14.4 Energy Conservation and Satellite Motion ­ 14.6 Escape Speed.notebook
January 27, 2017